1. Field of the Invention
The present invention generally relates to enclosure structures for protecting plants and, more particularly, is concerned with a self-supporting thermally-protective plant enclosure formed by a plurality of self-standing container bodies.
2. Description of the Prior Art
Members of the plant kingdom are sensitive to the environment in which they are grown. Members of this group include herbaceous and woody, annual, biennial, and perennial plants whose bulbs, flower parts, fruit, leaves, roots, seeds, stems, or tubers are used as food or for ornamental purposes. As used herein, the word "plant" will refer to all plants, even though the effects of adverse environment (e.g., climatic conditions or changes) on different types of plants may vary. Plants grown either in home gardens or in commercial fields which are used for food or ornament are referred to as the "crop".
Crops are produced commercially all over the world. More and more types of crops are transported over vast distances for sale in high volume in diverse markets. This global competition makes it essential to maximize the productivity of each individual plant which is grown to produce a crop, and to increase the duration of the growing season despite adverse climatic conditions.
Efforts to achieve these goals include building large structures, such as greenhouses, in which a controlled environment is maintained using artificial heat sources, for example. However, the use of such greenhouses is limited by the relatively high capital investment required for construction and provision of the equipment.
Efforts to provide a lower-cost, yet somewhat protective, environment for plants without using such greenhouse structures are illustrated by the devices disclosed in the prior patent art. Representative of such prior art are patents to Fry (U.K. Pat. No. 1,144,366), Morehead (U.S. Pat. No. 4,821,453) and Wallace et al (U.S. Pat. Nos. 4,137,667 and 4,267,665).
The Fry patent (U.K. Pat. No. 1,144,366) discloses a device for protecting a plant growth area which includes a plurality (three) translucent bags fused together and partially filled with water and apparently closed individually at their respective top ends to form three sides of a rough tetrahedron. The Fry device also includes a rigid inverted cup-shaped support cover which rests on the ground over and spaced by a layer of air from the plant growth area. The support cover supports the bags internally thereof such that the bags provide a layer of water over the small plant growth area. The rigid support also permits the passage of light to the small plant growth area.
The Morehead patent (U.S. Pat. No. 4,821,453) discloses a plant protector device which includes spaced outer and inner truncated-conical shaped hollow rigid continuous side walls and annular top and bottom end walls extending between and interconnecting the side walls. A top closure is provided to cap an opening through the top wall for supplying fluid into the hollow interior of the device defined between the side walls. The plant protector device is open at its top and bottom and is adapted to be placed over a seedling plant.
The first Wallace et al patent (U.S. Pat. No. 4,137,667) discloses a device for providing a protective covering for a growing plant which includes a bag holding water and being gathered and tied together by a tie at top and bottom portions to define an invaginated opening extending vertically upwardly from the bottom of the bag. This Wallace et al device also includes an inverted cup-shaped protective cover inside of and overlaid by the bag and disposed in the invaginated opening thereof. The cover rests on the ground and extends over the plant.
The second Wallace et al patent (U.S. Pat. No. 4,267,665) discloses a thermal protective covering for a plant which includes a double-walled structure having outer and inner walls being connected together along vertical lines spaced from one another about the circumference of the structure to define separate compartments between the walls. The walls are joined at the horizontally spaced vertical lines by heat sealing, adhesives, etc. The vertical lines are discontinuous to provide interconnections between the adjacent compartments to permit flow communication from one compartment to the next. The walls are closed at the bottom but open at the top to permit inflation by water added to the compartments. The top can be closed by a tie. Also, if desired the compartments can be non-communicating with one another and separately filled with water. Alternatively, the thermally protective cover could be constructed from a plurality of separately formed, non-fluid communicating sections. These sections could be formed as annular rings, elongated tubes or other configurations that could be fitted together to form a plant enclosure. The elongated tubes could be arranged side-by-side to enclose a growing area. This multi-tube device of the second Wallace patent is substantially similar to a plant covering device being marketed currently under the trademark Wall-O-Water.
The above-described prior art protective cover devices may likely constitute a small step in the right direction toward some improvement in functioning as a protective thermal environment for early plant growth. However, these prior art devices do embody a number of drawbacks such that none of the devices appears to provide an effective and viable configuration for satisfactory performance of such function. First, these prior art devices are or can only be opened at the top and so are incapable of allowing sufficient sunlight directly onto the plant and of releasing the humidity from around the plant to the external environment. The lack of sufficient direct sunlight and the overload of humidity produce plant growth lacking in strength. Second, some of the devices have to be completely removed from over the plant to have adequate access to the plant to practically apply side-dressed fertilizers. Third, because none of the prior art devices can be opened from the sides, applying pesticides to the undersides of leaves where most pests are found cannot be accomplished unless the devices are removed from the plant. Similarly, the application of side-dressed, granular fertilizers cannot be effectively accomplished without removing the prior art devices. Fourth, the second Wallace et al device which has the multiple tubes requires the filling of many small vertical tubes, a process that is tedious and time-consuming. Fifth, the prior art devices which are or can be opened only at the top are likely to cause damage to a plant when the device is pulled over the plant since it is likely that the plant is protruding through the open top of the device. Sixth, the high degree of flexibility of some of these prior art devices makes them unstable and difficult to handle and transport when either empty or full of water. The second Wallace et al patent cannot be used in a self-supporting configuration unless filled with a liquid.
Consequently, a need still exists for a plant enclosure which will avoid the drawbacks of the prior art devices and provide an effective protective thermal environment for early plant growth.